I gave a Zoom lecture last night on why people should care about native bees, and promised the audience (friends of Belmont Hills Library, in Bala Cynwyd, PA) that I’d share some links, photographs, and answers to some of the questions at the end. If you have any lingering questions or thoughts, please don’t hesitate to contact me. Good luck attracting bees, and thanks again for the invitation.
Here are some of the pics I’ve taken at bee hotels over the past several years. Sharing in case other beekeepers might recognize residents in their own hotels. There were bees, as one would expect, but also wasps, flies, and beetles.
Horn-faced mason bee (Osmia cornifrons). Very common at my hotels. Introduced from Asia in the 1970s. Details at BugGuide.
Giant resin bee (Megachile sculpturalis). Yes, also introduced, though more recently (~1994). Details at BugGuide.
Mock-orange scissor bee (Chelostoma philadelphi). So named because it prefers to collect pollen from trees in the genus Philadelphus (mock oranges). This is the only native member of the genus in the United States. Details at BugGuide.
Ancistrocerus antilope has shown up a few times at my hotels, but apparently prefers to nest in sumac and elder stems. It also is reported to use old mud-dauber nests. They are fun to watch because they provision nests with caterpillars. Details at BugGuide.
This is Euodynerus “Species F” at the moment. I.e., it’s one of several undescribed species in the genus (details here). Its biology is apparently unknown, so I’m hoping to get more of them in the future.
Parancistrocerus histrio is another wasp that feeds caterpillars to its brood. Details at BugGuide.
Auplopus mellipes provisions its nests with spiders. For a wonderful overview of their biology, please see post on Eric Eaton’s blog. (While there, I noticed he has a new book on wasps.)
Euodynerus schwarzi provisions nests with caterpillars. For identification tips, see blurb by Matthias Buck et al.; more pics are at BugGuide.
Euodynerus megaera is extremely similar to the above species but has black tibiae. At least females do (males are much harder to distinguish). It’s also a collector of caterpillars. More details by Buck et al.
Brown-legged grass-carrying wasp (Isodontia auripes) provision their nests with tree crickets. As their name suggests, they also carry grass, which they use to pack and seal the brood chamber. Details on BugGuide.
Here’s a photo of the grass-carrying wasp’s nesting plug that I took at Longwood Gardens. They have a beautiful bee hotel with hundreds of cells but as far as I could tell, only a few wasps had moved in.
Trypoxylon collinum provision their nests with spiders. Unlike many wasps and bees, the males in this genus actually help out around the nest. For details, please see this Instagram post. BugGuide has a page for the species but it contains little information.
Cuckoo wasp (Chrysis sp.). They are absolutely adorable. That said, they are also parasites of the above bees and wasps that are nesting at the hotel. They are very difficult to identify, so even getting them down to genus is rare. Here’s BugGuide’s page on the family.
The club-horned cuckoo wasp (Sapyga louisi) is another frequent parasitic wasp at my hotels. This one is patiently waiting to gain entrance to the nest of a mock-orange scissor bee. Details on BugGuide.
Leucospis affinis is another parasitic wasp that is almost always lurking around my bee hotel. It’s oddly variable in size. More details by Ari Grele at Insects of Cornell, at BugEric, and BugGuide.
Monodontomerus sp. (in Chalcidoidea) are extremely common parasites of mason bees. Please see this post at Nurturing Nature for great video and description of their life cycle. Additional details at BugGuide.
Digonogastra sp. These braconid wasps are parasites, but I’m not positive the ones I’ve seen at my bee hotels are targeting any of the residents. But they’ve shown up on at least two occasions so I think it’s a possibility.
Amobia sp. are flesh flies that develop on the provisions inside (for example) Trypoxylon nests. I’m not sure whether the larvae also eat the wasp larvae, but I’d suspect so. Details at BugGuide.
Houdini flies (Cacoxenus indagator) are newly introduced to the United States and are likely to ravage mason bee nests and the crops that depend on them for pollination. If you have bee hotel, this fly is reason #1 why you should use removable paper tubes that allow sorting of infested and uninfested brood cells. Without paper tubes your bee hotel will likely be a Houdini fly hotel. Crown Bees has information on how to clean your tubes.
Skin beetles (Dermestidae) are scavengers but can become serious pests of uncleaned mason bee hotels. Yet another reason to use only paper tubes fitted inside drilled holes, combined with a thorough cleaning of entire hotel (e.g., soak in bleach, scrub). Details on skin beetles at BugGuide.
The above is probably less than 1% of the species that might be found at a bee hotel that had a range of nesting-hole diameters. Noticeably absent are leaf-cutter bees, so that’s my photo resolution for 2021.
Like most monarch fans, I dutifully pack my yard with milkweed and hope the offering will somehow offset the effects of habitat loss and pesticide applications on population levels. But I’m not a complete idiot so I know that my contribution is probably rather inconsequential. Planting milkweeds for a few dozen monarchs is not really going to help population declines.
So this year I finally got around to something I’ve been meaning to do for years: give away lots of milkweed plants. My goal was to distribute free seedlings to several hundred people in my town (Swarthmore, Pennsylvania), ideally creating a concentration of milkweed that might make a difference. And because milkweeds are perennials and produce seeds that disperse with the wind, all of those initial milkweeds would do their reproductive duties for years, seeding vacant lots and such. Perhaps after a few years we will start seeing flocks of monarchs again (I’m an optimist).
This post summarizes how I grew the plants and gave them away, just in case anyone else might be nudged to do something similar. If one person in every town did this we might reverse the yearly declines in monarch populations.
Step one was to collect seeds. If you’ve never done it before it’s easy — just pick browning pods and let fully dry. Here’s a photograph from 2018 showing some swamp milkweed pods:
You don’t need to, but I decided to clean my seeds. Here’s the end product:
As seedlings emerged I’d transfer them to small Dixie cups. I soon covered almost every square inch of sunny space in my yard. (That’s my bee hotel, by the way.)
Then I started giving them away to people in town who had expressed an interest in growing milkweed. I put the seedlings into cheap paper cups and then delivered sets of threes to doorsteps. This used up about two dozen seedlings.
To get people to plant milkweed I thought it might be fun to leave pots around town along with, “please adopt us” notes. I gave away probably 100 this way. Usually the pots would be taken within an hour or so. It was fun leaving them in obscure spots around town, and I was hoping to build some curiosity about who was doing this and why.
Here’s the note I left with each set. I went with “rose milkweed” because I worried that “swamp milkweed” might be a turn-off for some. But same plant: Asclepias incarnata, my favorite milkweed. And it’s native.
Here are seedlings bound for one of the giveaway events. There were even more pots in the front.
Here’s my display table. I held the events on days when large crowds would be expected, so probably 95% of takers were people who didn’t realize they even wanted milkweed plants.
In total, I probably gave away 500 milkweed plants this year. I’m not positive it was a success but I think I noticed more monarchs around town this year. As anecdotal evidence, I wasn’t even trying to photograph a monarch when taking this picture:
If you have milkweed plants and seed pods, give it a try in 2020. It would be especially good if garden clubs across the country made this a priority.